Specifically, I have weekly lessons on my instrument, and it was just a horrible, garbled experience attempting to play instruments to each other.
(Of course, these are theoretical considerations, not a prediction for what actually happens in practice.)
64 kpbs, whichever codec, gets this small by cutting all frequencies outside of human speech. It cannot record instrumental sounds well.
Unfortunately, you're completely wrong about this. Sorry to undeceive you, I would have said the same a few years ago. Codecs, especially the best AAC encoders, and Opus, have improved drastically since 2005.
Listen for yourself to 64 kbps music samples made with the 2011 Opus. They're quite passable. https://people.xiph.org/~greg/opus/ha2011/ Certainly good enough for a WebRTC stream. No, it's not close to transparent, but it's going to be fine for a music lesson, there's no weird pitch shifts or anything.
To be clear, I mean quality indistinguishable from an audio CD, listening to songs in the quiet living room. I am not talking good enough for a stream or a phone call, that's a much lower bar.
For historic reference. Steam changed the codec for their voice chat around 2011 to something called SILK that seemed to be the parent of OPUS. It gave just enough quality to blast Ievan Polkka and Britney Spears in team fortress games and other players could recognize the song (noting it's very very low bitrate, it ain't great). By comparison, the previous encoding couldn't play songs at all, it butchered most frequencies so much that the audio was just lost.
That's right - SILK was a codec tuned for voice chat, not music. CELT is the other parent of OPUS and is tuned for music. (Opus uses a hybrid strategy that switches between codecs as necessary.) Don't just look at the benchmarks, at the bottom of the page you can click on the links and listen to a bunch of 64 kbps Opus samples. They're very, very good.
And no, they aren't indistinguishable from a CD. As I said in the original comment, they're more than good enough for high quality music streaming for a video chat.
> I'd really love to find out that codecs have halved audio size in the past half decade.
This has happened, to my ears at least. A little over a decade ago, I could not-infrequently tell a V2 MP3 (~196 kbps) from the FLAC. Took 256 kbps (~V0) to be reliably transparent. (I think it's improved marginally since then, V2 might be transparent almost all the time now.) These days, it's quite infrequent I can tell a 128 kbps Opus file from the FLAC. And the best codecs are quite passable even at 64 kbps.
Actually, Opus is "okay" even down to like 48 kbps. Try the sample here: https://people.xiph.org/~jm/opus/opus-1.2/
Those features are usually configurable in major video conferencing apps.
FYI, I saw some artist play on Zoom not so long ago, and the music was muted by their client. And they didn't know it happened or how to fix it. No software is immune from misconfiguration.